The present invention relates to a high frequency power supply device.
In order to obtain a small and lightweight high frequency power supply device having a ferroresonant circuit, a magnetic amplifier or the like as an output circuit; a high frequency AC power supply is required. In order to obtain a high frequency AC power supply from a DC power supply, a transistor inverter circuit is used. However, the switching loss of such an inverter circuit increases as the switching frequency rises. Such an increase in switching loss lowers the conversion efficiency of and increases heat generation in the transistor. This prevents production of a compact high frequency power supply device.
Regarding the output circuit, a ferroresonant circuit is less frequently prone to erratic operation due to noise such as electric/magnetic external noise, and has an innate protection function against overloading. However, a ferroresonant circuit operable under commercial frequencies is too heavy and large in size to be adopted as a power supply for recent electronic equipment. In addition to this, the iron loss increases in proportion to the switching frequency.
In a conventional power supply device, since the switching loss and the iron loss increase in proportion to the switching frequency, the conversion efficiency falls and heat generation from the switching element increases at higher frequencies. The need for dissipation of generated heat limits the degree to which the power supply device can be made compact in size.
In order to solve this problem and render the overall device small and lightweight, an inverter circuit which suffers only a small switching loss is required. An improvement in the output circuit such as a ferroresonant circuit, a magnetic amplifier or the like must also be made.